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CVE-2026-887788.8HighCWE-342

CVE-2026-88778: TCP Initial Sequence Number (ISN) prediction

Citrix NetScaler · ADC

Vendor fix available · Affected: Citrix NetScaler ADC · Exploitation: public proof of concept (unverified)

ExploitationProof of concept public

Not in CISA KEV as of catalogue 2026.11.10 (10 Nov)

  1. In CISA KEV: not seen
  2. Exploited (reported): not seen
  3. Scanning observed: not seen
  4. Proof of concept public1 public GitHub repository (unverified), listed by PoC-in-GitHub23 Oct
  5. Not established: not seen
0.7%probability of exploitation in the next 30 days
53rd percentile
050100

Higher than 53% of scored CVEs

8.8HighCVSS 4.0
LowHigh

DescriptionNVD

Predictable exact value from previous values vulnerability in Citrix NetScaler ADC and Citrix NetScaler Gateway. This issue affects ADC: before 14.1-73.37, before 13.1-64.23, before 14.1-73.37 FIPS, and before 13.1.37.279 FIPS and NDcPP; Gateway: before 14.1-73.37 and before 13.1-64.23.

What changed

  1. PoC-in-GitHub lists 1 public GitHub repository (unverified) PoC-in-GitHub

Coverage5 articles · 5 outlets

One row per outlet, in order of first report. First in our coverage: SecurityOnline, 27 Sep.

Full timeline
Quiet for 2 weekslast report 27 Oct5 articles5 outlets
27 Sep · SecurityOnline first22 Oct30 OctNow
  • Sun 27 Sep, 18:30 UTC. SecurityOnline, first report. Citrix NetScaler Zero Days Exploited to Attack VPN Appliances.
  • Sun 27 Sep, 20:47 UTC. CISA, its first report on the story. CISA Warns Attackers Are Exploiting Critical Citrix NetScaler Zero-Days.
  • Mon 28 Sep, 13:21 UTC. NCSC, its first report on the story. UK Cyber Agency Urges Action on Exploited Citrix NetScaler Flaws.
  • Fri 2 Oct, 17:05 UTC. Dark Reading, its first report on the story. Citrix NetScaler Zero Days Exploited as Vendors Take Different Risks.
  • Tue 27 Oct, 11:55 UTC. SecurityWeek, its first report on the story. Citrix patches NetScaler flaws after active exploitation.
All coveragerunning total5SecurityOnl…1CISA1NCSC1Dark Reading1SecurityWeek128 Sep13 Oct28 OctNow
  • First report
  • Article
  • Official notice
  • Running total
Show as table
5 articles about CVE-2026-88778 from 5 outlets
Published (UTC)OutletHeadline
27 Sep 18:30SecurityOnlineCitrix NetScaler Zero Days Exploited to Attack VPN Appliances
27 Sep 20:47CISACISA Warns Attackers Are Exploiting Critical Citrix NetScaler Zero-Days
28 Sep 13:21NCSCUK Cyber Agency Urges Action on Exploited Citrix NetScaler Flaws
2 Oct 17:05Dark ReadingCitrix NetScaler Zero Days Exploited as Vendors Take Different Risks
27 Oct 11:55SecurityWeekCitrix patches NetScaler flaws after active exploitation
  1. Citrix patches NetScaler flaws after active exploitation
    SecurityWeek · mentions it in passing
  2. Citrix NetScaler Zero Days Exploited as Vendors Take Different Risks
    Dark Reading · mentions it in passing
  3. UK Cyber Agency Urges Action on Exploited Citrix NetScaler Flaws
    NCSC · official notice · mentions it in passing
  4. CISA Warns Attackers Are Exploiting Critical Citrix NetScaler Zero-Days
    CISA · official notice · mentions it in passing
  5. Citrix NetScaler Zero Days Exploited to Attack VPN Appliances
    SecurityOnline · first in our coverage · mentions it in passing

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References

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